The effect of physical characteristics and field position on the shoulder and elbow injuries of 490 baseball players: confirmation of diagnosis by magnetic resonance imaging

A Number of Modifiable and Nonmodifiable Factors Increase the Risk for Elbow Medial Ulnar Collateral Ligament Injury in Baseball Players: A Systematic Review

PURPOSE

To analyze the current literature regarding risk factors associated with medial ulnar collateral ligament (MUCL) injury in baseball players and to serve as a robust source for identifying modifiable risk factors that once optimized, have the potential to reduce injury risk.

METHODS

Comprehensive search of the available literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Studies were included if they evaluated risk factors for MUCL injuries in the elbow of baseball players. Risk of bias assessment was performed via Methodological Index for Non-randomized Studies (MINORS) scoring system. The Oxford Centre for Evidence-Based Medicine was used to determine level of evidence. Variables of interest; player age, position, shoulder motion, humeral retrotorsion, joint laxity, strength, balance, geography, velocity, pitch count, pitch types, throwing volumes, and throwing mechanics were recorded.

RESULTS

Twenty-one studies were included in this systematic review. MINORS scores ranged from 75 to 87%, and variables demonstrated significant heterogeneity. Performance-based risk factors for MUCL injury included: increased pitch count (both annual and per game), higher percentage of fastballs thrown, smaller pitch repertoire, and/or a loss of pitching velocity. Biomechanical studies demonstrated the relationship between decreased shoulder range of motion (total ROM, ER, IR, and abduction), increased humeral retrotorsion, increased elbow valgus opening in the throwing arm, lower Y-Balance score, and increased lateral release position to increased MUCL injury.

CONCLUSION

Risk factors for MUCL injury can generally be categorized into 4 primary groups: 1) various player demographics and characteristics, 2) throwing too hard (high velocity), 3) throwing too much (pitch count/volume), and 4) throwing with poor mechanics. In this systematic review, the most significant nonmodifiable risk factors for MUCL injuries included: increased glenohumeral retrotorsion and elbow valgus opening. The most consistent modifiable risk factors included: total shoulder range of motion, pitch count, pitch selection, Y balance score, and lateral release position. Pitch velocity was inconsistent in literature, but most studies found this as a risk for injury. These risk factors may serve as appropriate targets for future evidence-based injury mitigation strategies.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

Glenohumeral Instability and Arm Pain in Overhead Throwing Athletes: A Correlational Study

Background

The overhead activity of throwing a baseball is arguably the most demanding athletic endeavor placed on the glenohumeral (GH) joint. Previous studies illustrate that 75-80% of baseball players will experience some degree of upper extremity (UE) pain. GH instability is thought to play a role.

Purpose

The purpose of this study was to investigate the relationship between GH joint hypermobility and instability with measures of arm pain and performance in overhead throwing athletes.

Methods

Actively competing baseball pitchers were recruited and evaluated once with the anterior-posterior Load and Shift examination procedure, the Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire (KJOC), and the Functional Arm Scale for Throwers (FAST). Multivariate analysis was performed to identify correlation between severe GH capsular laxity (GH instability), mild capsular laxity (GH hypermobility), no capsular laxity (GH normal), and presence of shoulder pain when pitching.

Study Design

Cross-sectional Study.

Results

Forty-five pitchers were evaluated, 62.2% of throwing shoulders were classified normal stability, 26.7% were classified hypermobile, and 11.1% were classified unstable. Average KJOC scores for pitchers with the three mobility categories were 66.1 (normal), 59.7 (hypermobile), and 45.0 (unstable). Average FAST scores among the pitchers were 19.9 (normal), 34.2 (hypermobile), and 32.2 (unstable). Pitchers with GH instability and GH hypermobility demonstrated increased arm pain compared to athletes with normal GH joints; KJOC scores of 3.2, 5.5, and 7.4 (p = 0.0007), respectively.

Conclusion

Pitchers with GH instability and hypermobility demonstrated significantly increased ratings of arm pain compared to pitchers with no capsular laxity.

Level of Evidence

3b.

Return-to-Play and Competitive Outcomes After Ulnar Collateral Ligament Reconstruction Among Baseball Players: A Systematic Review

Background:

Ulnar collateral ligament (UCL) reconstruction (UCLR) is very common in baseball. However, no review has compared the return-to-play (RTP) and in-game performance statistics of pitchers after primary and revision UCLR as well as of position players after UCLR.

Purpose:

To review, synthesize, and evaluate the published literature on outcomes after UCLR in baseball players to determine RTP and competitive outcomes among various populations of baseball players.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A literature search including studies between 1980 and November 4, 2019, was conducted for articles that included the following terms: ulnar collateral ligament, elbow, medial collateral ligament, Tommy John surgery, throwing athletes, baseball pitchers, biomechanics, and performance. To be included, studies must have evaluated baseball players at any level who underwent UCLR (primary or revision) and assessed RTP and/or competitive outcomes.

Results:

A total of 29 studies with relatively high methodological quality met the inclusion criteria. After primary UCLR, Major League Baseball (MLB) pitchers returned to play in 80% to 97% of cases in approximately 12 months; however, return to the same level of play (RTSP) was less frequent and took longer, with 67% to 87% of MLB pitchers returning in about 15 months. RTP rates for MLB pitchers after revision UCLR were slightly lower, ranging from 77% to 85%, while RTSP rates ranged from 55% to 78%. RTP rates for catchers (59%-80%) were generally lower than RTP rates for infielders (76%) and outfielders (89%). All studies found a decrease in pitching workloads after UCLR. Fastball usage may also decrease after UCLR. Changes in earned run average and walks plus hits per inning pitched were inconclusive.

Conclusion:

Pitchers returned to play after UCLR in approximately 12 months and generally took longer to return to their same level of play. Pitchers also returned to play less frequently after revision UCLR. After both primary and revision UCLR, professional pitchers experienced decreased workloads and potentially decreased fastball usage as well. Catchers may RTP after UCLR less frequently than pitchers, infielders, and outfielders possibly because of the frequency of throwing in the position. These results will help guide clinical decision making and patient education when treating UCL tears in baseball players.

Stride-Phase Kinematic Parameters That Predict Peak Elbow Varus Torque

Background:

During baseball pitching, a high amount of elbow varus torque in the arm cocking-to-acceleration phase is thought to be a biomechanical risk factor for medial elbow pain and injury. The biomechanics of the stride phase may provide preparation for the arm cocking-to-acceleration phase that follows it.

Purpose:

To determine the kinematic parameters that predict peak elbow varus torque during the stride phase of pitching.

Study Design:

Descriptive laboratory study.

Methods:

Participants were 107 high school baseball pitchers (age range, 15-18 years) without shoulder or elbow problems. Whole-body kinematics and kinetics during fastball pitching were analyzed using 3-dimensional measurements from 36 retroreflective markers. A total of 26 kinematic parameters of the upper and lower limbs during the stride phase leading up to the stride foot contact were extracted for multiple regression analysis to assess their combined effect on the magnitude of peak elbow varus torque.

Results:

Increased wrist extension, elbow pronation, knee flexion on the leading leg, knee extension on the trailing leg at stride foot contact, and upward displacement of the body’s center of mass in the stride phase were significantly correlated with decreased peak elbow varus torque (all P < .05). Moreover, 38% of the variance in peak elbow varus torque was explained by a combination of these 5 significant kinematic variables (P < .001).

Conclusion:

We found that 5 kinematic parameters during the stride phase and the combination of these parameters were associated with peak elbow varus torque. The stride phase provides biomechanical preparation for pitching and plays a key role in peak elbow varus torque in subsequent pitching phases.

Clinical Relevance:

The present data can be used to screen pitching mechanics with motion capture assessment to reduce peak elbow varus torque. Decreased peak elbow varus torque is expected to reduce the risk of elbow medial pain and injury.

Biomechanical analysis of the pitching characteristics of adult amateur baseball pitchers throwing standard and lightweight balls

[Purpose] The purpose of this study was to determine the relationship between pitching weight and pitching mechanics, including ball reaction force (BRF) and temporal parameters, for the prevention of throwing injury in adult amateur pitchers. [Participants and Methods] Twenty adult male amateur pitchers (mean age, height, and body mass: 26 ± 3.4 years, 1.7 ± 0.03 m, and 71.6 ± 9.5 kg, respectively) randomly pitched light (110 g) and heavy (145 g) baseballs at maximum velocity. Kinematic, kinetic, and temporal parameters were compared between the light and heavy balls. [Results] Pitching heavy balls significantly increased the BRF to 9.2 N and maximum trunk rotation angular velocity to 26.2°/sec, and decreased the ball speed to 1.4 m/sec and upper limb joint torque efficiency and shoulder internal rotation angular velocity at the moment of ball release at 250.8°/sec. Furthermore, the peak temporal kinetic parameters until ball release appeared early in the throwing of the heavy ball. [Conclusion] Adult amateur pitchers who pitched heavy balls had greater BRF; had decreased upper limb joint torque efficiency, ball speed, and arm angular velocity; and reached maximum kinetics early. Adult amateur pitchers may be at risk of throwing injuries due to throwing of heavy balls.

Maturation-dependent findings in the shoulders of pediatric baseball players on magnetic resonance imaging

PURPOSE

To compare the prevalence and characteristics of shoulder osseous and soft tissue findings on magnetic resonance imaging (MRI) with respect to skeletal maturation in symptomatic pediatric baseball players without a history of acute trauma.

METHODS

The IRB-approved, HIPAA-compliant retrospective study analyzed 87 consecutive pediatric baseball players (86 boys and 1 girl; mean age, 15.4 ± 2.1 years) with shoulder MRI performed between March 1, 2012 and September 30, 2017. In consensus, two radiologists assessed the MRI studies for findings involving the humerus, the glenoid, the labrum, the rotator cuff, and the acromioclavicular joint. Exact Cochran-Armitage trend and Mantel-Haenszel Chi-square tests were used to investigate the association between these findings and skeletal maturation.

RESULTS

The mean ages between players who are skeletally immature (37 shoulders), maturing (26 shoulders), and matured (24 shoulders) were significantly different (p < 0.001). Bone marrow edema (p < 0.001) and sclerosis (p < 0.001) within the proximal humeral metaphysis decreased with skeletal maturation. Glenoid remodeling (p = 0.038) was more severe in the skeletally immature players and the prevalence of Bennett lesions (p = 0.048) increased with skeletal maturation. The prevalence of labral tears, rotator cuff tendinosis, and acromioclavicular joint separation did not significantly change with skeletal maturation.

CONCLUSIONS

The change in the prevalence of findings within the proximal humerus and glenoid with skeletal maturation suggest differences in the distribution of stress within the shoulders of pediatric baseball players during development.

Association Between Parental Understanding of Pitch Smart Guidelines and Youth Baseball Player Injuries

Background

Injuries continue to rise among youth baseball players despite extensive research into prevention and the availability of throwing guidelines such as Pitch Smart. More research is needed to understand whether adherence to the current guidelines decreases injuries.

Purpose

To understand the degree to which parents are aware of the Pitch Smart guidelines, whether parents adhere to the guidelines, and whether adherence results in decreased injuries in youth baseball players.

Study Design

Cross-sectional study.

Methods

An anonymous, internet-based survey consisting of 44 items was distributed to parents of adolescent baseball players affiliated with various youth baseball organizations across the midwestern United States; 15 items on the survey served as assessment questions of the Pitch Smart guidelines. Absolute and percentage correct scores were calculated and compared by use of a Student t test. A chi-square analysis was used to compare discrete data. A binary logistic regression analysis was conducted to determine whether showcase participation predicted player injury.

Results

A total of 853 parents completed the survey. The mean ± SD age of the players on whom parents reported was 11.37 ± 3.5 years (range, 6-20 years). Among the cohort, 422 players regularly pitched. Regarding Pitch Smart guidelines, the percentage of correct answers by parents was 55.44% ± 0.3% for a player with a reported injury history and 62.14% ± 0.2% for a player without an injury history (P = .012). The number of correct answers was 8.03 ± 4.0 for the group with an injury history and 9.17 ± 3.2 for the group with no history of injury (P = .004). Binary logistic regression analysis, which controlled for age, indicated that showcase participation (P = .001, β = 1.043 ± 0.026, R² = 0.178) was a significant predictor of player injury.

Conclusion

Pitchers are at an increased risk of injury compared with nonpitchers. Parents who are knowledgeable about the Pitch Smart throwing guidelines and actively follow them are significantly less likely to have a child with an injury. Excessive showcase participation is predictive of player injury when the analysis controls for age.

Risk Factors for Elbow and Shoulder Injuries in Adolescent Baseball Players: A Systematic Review

BACKGROUND

The incidence of shoulder and elbow injuries among adolescent baseball players is on the rise. These injuries may lead to surgery or retirement at a young age.

PURPOSE

To identify independent risk factors for elbow and shoulder injuries in adolescent baseball players. A secondary aim was to determine whether the literature supports the Major League Baseball and USA Baseball Pitch Smart guidelines.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines utilizing MEDLINE, SPORTDiscus, and Web of Science. Because of study heterogeneity, a quantitative synthesis was not performed. A qualitative review was performed on 19 independent risk factors for elbow and shoulder injuries in adolescent baseball players. Level of evidence was assigned per the Oxford Centre for Evidence-Based Medicine Working Group, and risk of bias was graded per the Newcastle-Ottawa Scale.

RESULTS

Twenty-two articles met criteria for inclusion. Of the 19 independent variables that were analyzed, age, height, playing for multiple teams, pitch velocity, and arm fatigue were found to be independent risk factors for throwing arm injuries. Pitches per game appears to be a risk factor for shoulder injuries. Seven independent variables (innings pitched per game, showcase participation, games per year, training days per week, pitch type, shoulder external rotation, and shoulder total range of motion) do not appear to be significant risk factors. The data were inconclusive for the remaining 6 variables (weight, months of pitching per year, innings or pitches per year, catching, shoulder horizontal adduction, and glenohumeral internal rotation deficit).

CONCLUSION

The results from this study demonstrate that age, height, playing for multiple teams, pitch velocity, and arm fatigue are clear risk factors for throwing arm injuries in adolescent baseball players. Pitches per game appears to be a risk factor for shoulder injuries. Other variables are either inconclusive or do not appear to be specific risk factors for injuries.

Risk factors for ulnar collateral ligament injury in professional and amateur baseball players: a systematic review with meta-analysis

BACKGROUND

Risk factors for ulnar collateral ligament injury (UCLI) are unclear despite increasing injury rates. We sought to summarize UCLI risk factors in baseball players.

METHODS

A computer-assisted search of 4 databases was performed using keywords related to UCLI risk factors. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used for study methodology. Odds ratios and 95% confidence intervals were calculated for dichotomous outcomes, and mean differences and 95% confidence intervals were calculated for continuous outcomes using a random-effects model.

RESULTS

Thirteen studies qualified for inclusion. A greater nondominant (ND) shoulder internal rotation (IR) range of motion (ROM) at 90° abduction arm demonstrated strong evidence as a significant risk factor for UCLI (P < .001) compared with a control group. Mean overall velocity (P < .001), fastball velocity (P < .001), changeup velocity (P = .03), and curveball velocity (P = .01), as well as fewer years of player experience (P < .001), less humeral retrotorsion in the ND arm (P < .001), and greater absolute side-to-side differences in retrotorsion (P = .006) were all moderate-evidence risk factors compared with control groups. Strong evidence suggests total ROM arc at 90° abduction in the dominant arm was not a risk factor for UCLI (P = .81).

CONCLUSIONS

Greater ND shoulder IR ROM and less humeral retrotorsion (in professional and amateur players) as well as pitching velocity (in professional players) demonstrated strong to moderate evidence as risk factors for UCLI. Dominant arm total arc of motion, external, or IR ROM were not risk factors for UCLI. Standardized collection and reporting of risk factors is recommended to more clearly elucidate definitive risk factors for UCLI.

Effectiveness of ultrasonography screening and risk factor analysis of capitellar osteochondritis dissecans in adolescent baseball players

BACKGROUND

Capitellar osteochondritis dissecans (COCD) is a common elbow injury in young baseball athletes. It may be asymptomatic at the early stage and may progress if left untreated. This study investigated the effectiveness of ultrasonography (US) screening for COCD in adolescent baseball players and identified risk factors of COCD.

METHODS

A cross-sectional analysis study was conducted among baseball athletes aged 12 to 18 years. US screening of the throwing elbow was performed in all participants, and additional magnetic resonance imaging (MRI) was arranged for those with abnormal screening results. The prevalence of COCD was calculated according to MRI results. The US findings were compared with MRI findings. Data for characteristics, joint range of motion, and quality of pain were collected and analyzed using a logistic regression model to identify the risk factors of COCD.

RESULTS

A total of 299 adolescent baseball players were screened, and 17 were found to have COCD according to US findings. MRI was performed in 15 of these 17 players, and the MRI findings further confirmed COCD in 10 players (66.7%). The presence of elbow pain while at rest, body height, and age at introduction to baseball were predictors of COCD.

CONCLUSIONS

Although the effectiveness of diagnosing stage 1 COCD is satisfactory, US is a helpful tool for detecting stage 2 and higher-stage COCD. Elbow resting pain, lower body height, and introduction to baseball at a younger age are risk factors for COCD.

The prevalence of scapular malalignment in elementally school aged baseball player and its association to shoulder disorder

BACKGROUND

Various shoulder disorders have been reported to be associated with scapulothoracic joint dysfunction in adult overhead athletes. However, little is known about the prevalence of scapular malalignment and its relationship to shoulder injuries in skeletally immature baseball players. The purpose of the current study was to investigate the prevalence of scapular malalignment in elementary school-aged baseball players, as well as its association with shoulder disorder.

METHODS

One hundred sixty-nine baseball players in higher elementary school grades (aged 11-12 years) were enrolled in this study. Shoulder pain experience pain over the previous one year, as well as other individual and environmental factors were surveyed by a self-completed questionnaire. Scapula malalignment was assessed using still images of both arms both at the side and in an elevated position. The relative position of the dominant scapula to the non-dominant side was assessed by two independent examiners.

RESULTS

Scapular malalignment was observed in 126 subjects (74.6%), and the dominant scapula tended to deviate inferiorly and medially, as well as tilt anteriorly, compared with the non-dominant side. Forty-four of the 169 subjects (23.8%) experienced shoulder pain over the one year period. The prevalence of shoulder pain was significantly increased with the increasing scapular anterior tilt and the superior shift of the dominant scapula, whereas no significant correlation between shoulder pain and scapular horizontal shift or upward-downward rotation was observed.

CONCLUSION

About three-quarters of the elementary school-aged baseball players in the current study presented with scapular malalignment, and those with anterior tilt and superior shift of the dominant scapula were at higher risk of shoulder pain.

Increased pitch velocity and workload are common risk factors for ulnar collateral ligament injury in baseball players: a systematic review

Importance

Ulnar collateral ligament (UCL) injuries commonly occur in baseball players. Strategies for injury prevention have long been accepted without clinical data informing which risk factors lead to serious injury.

Objective

The objective of this study was to systematically review the impact of various pitching-related risk factors for UCL injury in baseball players from all levels of play.

Evidence review

The electronic databases MEDLINE, EMBASE and PubMed were systematically searched until 4 March 2018, and pertinent data were abstracted by two independent reviewers. Search terms included ‘ulnar collateral ligament’, ‘medial ulnar collateral ligament’, ‘Tommy John’, ‘risk’ and ‘association’. Inclusion criteria were English-language studies, level of evidence I–IV and studies reporting risk factors for UCL injury of the elbow in baseball players. Study quality was assessed using the methodological index for non-randomised studies (MINORS) criteria. The results are presented in a narrative summary.

Findings

Pitching practices (workload and pitch characteristics) were reported in 9/15 studies. Specifically, three of four studies (n=1810) reported increased pitch workload as a risk factor for native UCL injury (p<0.001 to 0.02). The most common pitch characteristic reported was pitch velocity with four of five studies showing increased velocity being significantly associated with native UCL injury (p<0.01 to 0.02). Biomechanical risk factors reported were increased humeral retrotorsion (two studies; n=324), poor lower extremity and trunk balance (one study; n=42) and loss of total arc of shoulder motion (two studies; n=118), all significantly associated with UCL injury (p<0.0001 to 0.05). One of three studies assessing pitch workload as a risk factor for re-rupture of UCL reconstruction found a significant association (p<0.01).

Conclusions and relevance

Pitching practices, reflected by increased pitch workload and velocity, were most commonly associated with UCL injury; however, the definition of workload (number of pitches per game, inning or season) was inconsistently reported. Biomechanical risk factors were less commonly reported and lack sufficient evidence to recommend preventative strategies. More quality data is needed to refine the current recommendations for injury prevention in baseball players.

Level of evidence

III.

Coexistence of Trunk or Lower Extremity Pain with Elbow and/or Shoulder Pain among Young Overhead Athletes: A Cross-Sectional Study

Elbow or shoulder injuries are common in overhead sports. Because energy derived from the lower extremity passes through the trunk to the upper extremity in overhead motion, a break in such a kinetic chain could lead to arm injuries. However, there is only limited information about the role of the trunk and lower extremity support in preventing elbow or shoulder injuries. This study aimed to explore the association of trunk and lower extremity pain with elbow/shoulder pain among young overhead athletes. We conducted a cross-sectional study using self-reported questionnaires mailed to young athletes belonging to the Miyagi Amateur Sports Association. The final study population comprised 2,215 young athletes playing baseball (n = 1,422), volleyball (n = 546), softball (n = 14), handball (n = 28), tennis (n = 110), or badminton (n = 95). The median age of the participants was 11 years (range: 6 to 15 years). Multiple logistic regression analysis revealed the higher prevalence of elbow and/or shoulder pain in athletes with back pain (OR = 5.52, 95% CI = 3.51-8.69), hip pain (OR = 6.13, 95% CI = 3.35-11.22), knee pain (OR = 2.28, 95% CI = 1.48-3.51), and foot pain (OR = 3.03, 95% CI = 1.95-4.72), compared with those without pain. We propose that trunk or lower extremity pain is significantly associated with elbow or shoulder pain among young overhead athletes. Assessing for pain in trunk or lower extremity, as well as elbow and/or shoulder pain, may help prevent serious injuries in young overhead athletes.

Epidemiology of Shoulder and Elbow Injuries Among United States High School Baseball Players: School Years 2005-2006 Through 2014-2015

BACKGROUND

Shoulder and elbow injuries are common in young athletes, especially high school baseball players. Understanding the risk factors associated with baseball injuries is an essential first step in the development of injury prevention strategies.

PURPOSE

To provide a comprehensive understanding of the epidemiology of shoulder and elbow injuries among high school baseball players in the United States.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

Baseball-related injury data were obtained from the National High School Sports-Related Injury Surveillance Study using High School RIO (Reporting Information Online), an Internet-based sports injury surveillance system. Athletic trainers from high schools across the country uploaded data regarding athlete-exposures (AEs) (defined as practice or game participation) and shoulder and elbow injuries from the school years 2005-2006 through 2014-2015.

RESULTS

A total of 241 shoulder injuries and 150 elbow injuries occurred during 1,734,198 AEs during the study period, for an overall shoulder injury rate of 1.39 per 10,000 AEs and an overall elbow injury rate of 0.86 per 10,000 AEs. The overall rates of injury were higher in competitions compared with practices for shoulders (rate ratio, 1.44; 95% CI, 1.11-1.85) and elbows (rate ratio, 2.15; 95% CI, 1.56-2.96). The majority of shoulder (39.6%) and elbow (56.9%) injuries were sustained by pitchers, and most injuries were chronic and caused by overuse. Position players were more likely to sustain injuries by contact with the playing surface or apparatus. For pitchers, muscle strains were the most common shoulder injuries (38.7%), while ligament sprains were the most common elbow injuries (42.7%). The majority of pitchers with shoulder (70.8%) and elbow (64.6%) injuries returned to play within 21 days. Among pitchers, a higher proportion of elbow injuries (11.4%) resulted in medical disqualification compared with shoulder injuries (5.6%). Among pitchers, the majority of shoulder (89.2%) and elbow (96.4%) injuries were managed nonsurgically.

CONCLUSION

Shoulder and elbow injury rates and patterns in high school baseball players differed between field positions (pitchers vs position players) and by type of exposure (practice vs competition). This study suggests several areas of emphasis for targeted injury prevention interventions, most notably limiting fatigue and preventing overuse injuries.

Shoulder Injuries in Pediatric Athletes

Shoulder injuries in pediatric athletes are typically caused by acute or overuse injuries. The developing structures of the shoulder lead to injury patterns that are distinct from those of adult athletes. Overuse injuries often affect the physeal structures of the proximal humerus and can lead to pain and loss of sports participation. Shoulder instability is common in pediatric athletes, and recurrence is also a concern in this population. Fractures of the proximal humerus and clavicle are typically treated with conservative management, but there is a trend toward surgical intervention.

Reliability of Magnetic Resonance Imaging Signs of Posterolateral Rotatory Instability of the Elbow

PURPOSE

To evaluate radiographic signs of posterolateral rotatory instability (PLRI) on magnetic resonance imaging (MRI). The goal was to establish objective radiographic criteria to aid in the diagnosis of PLRI.

METHODS

The MRI scans of 60 patients were evaluated retrospectively. Two study groups were compared. Group 1 (n = 30) consisted of unstable elbows in which PLRI was confirmed by clinical examination and arthroscopy. Group 2 (stable; n = 30) served as the control group. Patients in group 2 had transient epicondylitis without clinical suspicion of instability. Joint incongruity was analyzed for sagittal views through the radial head and the coronoid tip and for coronal and axial views. Interobserver and intra-observer reliability were evaluated.

RESULTS

In the sagittal view through the radial head, average radiocapitellar incongruity differed significantly between groups 1 and 2. In addition, mean ulnohumeral incongruity in an axial view through the motion axis of the distal humerus showed significant differences between groups. Sagittal views through the tip of the coronoid and coronal views did not reveal significant differences in patients with unstable elbows compared with the control group.

CONCLUSIONS

The current study provides useful MRI criteria indicative of PLRI when combined with physical examination. Cutoff points of 1.2 mm for radiocapitellar incongruity (sagittal view) and 0.7 mm for axial ulnohumeral incongruity (axial view) are suitable to screen for PLRI. Radiocapitellar incongruity greater than 2 mm and axial ulnohumeral incongruity greater than 1 mm are highly suspicious of elbow instability.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Examination of the elbow: current concepts

The elbow's complex anatomy and synergism of bony and ligamentous stabilizers make physical examination challenging. Adequate elbow assessment is essential for accurate diagnosis and initiating proper treatment. Isolated elbow injuries are rare; fractures should be interpreted as proxies for associated, often unappreciated, soft tissue injuries. A careful elbow examination informs the need for and interpretation of radiological studies, including fluoroscopy, magnetic resonance imaging, and computed tomography scanning.

Preliminary development of a clinical prediction rule for treatment of patients with suspected SLAP tears

PURPOSE

To use the clinical prediction rule process to identify patient variables, measured on initial clinical presentation, that would be predictive of failure to achieve satisfactory improvement, while following a rehabilitation program, in the modification of SLAP injury symptoms and dysfunction.

METHODS

A cohort of patients received the clinical diagnosis of a SLAP lesion based on specific history and examination findings and/or magnetic resonance imaging. They underwent a physical examination of the kinetic chain and shoulder, including tests for labral injury. Patients followed a standardized physical therapy program emphasizing restoration of demonstrated strength, flexibility, and strength-balance deficits. At 6 weeks' follow-up, patients were re-evaluated and divided into those recommended for surgery (RS) and those not recommended for surgery (NRS). Bivariate logistic regression was performed to identify the best combination of predictive factors.

RESULTS

Fifty-eight patients (aged 39 ± 11 years, 45 men) were included. Of these, 31 (53%) were categorized as NRS and 27 (47%) as RS. The presence of a painful arc of motion (odds ratio, 3.95; P = .024) and the presence of increased forward scapular posture (odds ratio, 1.27; P = .094) on the injured side were predictive of being in the RS group. This finding indicates that the odds of being in the RS group increased 4 times when a positive painful arc was present and increased 27% with every 1-cm increase in involved anterior shoulder posture.

CONCLUSIONS

A structured rehabilitation program resulted in modification of symptoms and improved function at 6 weeks' follow-up in over half of patients in the study group. On initial evaluation, the presence of a painful arc of overhead motion, indicating loss of normal glenohumeral kinematics, and the presence of forward shoulder posture, indicating an altered scapular position, represent negative predictive factors for success of rehabilitation. Future validation of the model in a larger population is necessary.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

The association of foot arch posture and prior history of shoulder or elbow surgery in elite-level baseball pitchers

STUDY DESIGN

Case-control.

OBJECTIVES

The specific aim of this study was to examine the association between abnormal foot arch postures and a history of shoulder or elbow surgery in baseball pitchers.

BACKGROUND

Pitching a baseball generates forces throughout the musculoskeletal structures of the upper and lower limbs. Structures such as the longitudinal arch of the foot are adaptable to stresses over time. Repeated pitching-related stresses may contribute to acquiring abnormal foot arch postures. Inversely, congenitally abnormal foot arch posture may lead to altered stresses of the upper limb during pitching.

METHODS

A convenience sample of 77 pitchers was recruited from a Division I university team and a professional baseball franchise. Subjects who had a history of shoulder or elbow surgery to the pitching arm were classified as cases. Subjects who met the criteria for classification of pes planus or pes cavus based on longitudinal arch angle were classified as having abnormal foot arch posture. Odds ratios were calculated to examine the association between abnormal foot arch posture and pitching-arm injury requiring surgery.

RESULTS

Twenty-three subjects were classified as cases. The odds of being a case were 3.4 (95% confidence interval: 1.2, 9.6; P = .02) times greater for subjects with abnormal foot arch posture and 2.9 (95% confidence interval: 1.0, 8.1; P = .04) times greater for subjects with abnormal foot posture on the lunge leg.

CONCLUSION

Abnormal foot arch posture and a surgical history in the pitching shoulder or elbow may be associated. Because the foot and its arches are adaptable and change over time, the pathomechanics of this association should be further explored.

Medial elbow injury in young throwing athletes

This report reviews the anatomy, overhead throwing biomechanics, injury mechanism and incidence, physical examination and diagnosis, diagnostic imaging and conservative treatment of medial elbow injuries in young throwing athletes. Based on the information a clinical management decision-making algorithm is presented.

Elbow injuries in the young athlete--an orthopedic perspective

Elbow injuries in young athletes are increasing with these athletes specializing in a single sport at an early age and participating in their chosen sport at a high level year-round. The majority of these injuries occur from valgus loading of the elbow, either repetitively causing an overuse injury or more acutely resulting in a fracture or dislocation. Capitellar osteochondritis dissecans, medial epicondyle injuries and ulnar collateral ligament injuries are three of the most common elbow injuries occurring in young athletes.

Shoulder kinematics during pitching: comparing the slide step and traditional stretch deliveries

Although studies have investigated the traditional stretch delivery, there is little biomechanical data describing the slide step delivery in baseball pitchers. Thus, the purpose of this study was to compare shoulder kinematics across the traditional stretch and slide step deliveries. To collect kinematic data from thirty-seven high school baseball pitchers, electromagnetic sensors recording at 140 Hz were affixed to various body segments. The average of those data from the three fastest pitches passing through the strike-zone were analyzed for each delivery. At the instances of front foot contact and ball release, no differences were observed between the two deliveries. At the instant of maximum shoulder external rotation, differences were observed between the two deliveries with regard to plane of elevation (t(72)=4.19, p<.001), elevation (t(72)=-3.38, p<.001), and axial rotation (t(72)=2.49, p=.015). The mechanical differences observed between the two delivery styles may have the potential to impact both performance and injury. Also, based on these results there may be a tradeoff between injury risk and performance. Thus, further study is warranted in an effort to identify the interrelationships between injury risk, performance, and pitching kinematics when throwing from the stretch position.

Agreement in the classification and treatment of the superior labrum

BACKGROUND

The Snyder classification scheme is the most commonly used system for classifying superior labral injuries. Although this scheme is intended to be used for arthroscopic visual classification only, it is thought that other nonarthroscopic historical variables also influence the classification.

PURPOSE

This study was conducted to evaluate the intrasurgeon and intersurgeon agreement in classifying variable presentations of the superior labrum and to evaluate the influence of clinical variables on the classification and treatment choices of surgeons.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

A group of arthroscopic shoulder surgeons were asked to rank in order of importance clinical variables considered in diagnosing and treating the superior labrum. The surgeons then watched 50 arthroscopic videos of the superior labrum, ranging from normal to pathologic, on 3 different occasions. The first and third viewings were accompanied by no clinical information. The second viewing was accompanied by a detailed clinical vignette for each video. The surgeons selected a classification and treatment for each video.

RESULTS

A patient's job/sport, age, and physical examination findings were considered the most important clinical variables surgeons consider during management of the superior labrum. Comparing the 2 viewings without clinical information, surgeons selected a different classification 28.5% of the time from the first to the second time. A different classification was chosen 71.5% of the time when the surgeon was supplied a clinical vignette at the subsequent viewing. Similarly, the treatment selected changed in 36% and 69.1% of cases when viewed again without vignettes and with vignettes, respectively. Intersurgeon agreement was moderate without clinical vignettes and fair with vignettes. Historical, physical examination, and surgical observations were found to influence the odds of change of classification.

CONCLUSION

There is significant intrasurgeon and intersurgeon variability in classification and treatment of the superior labrum. Clinical historical, examination, and surgical findings influence classification and treatment choices.